This application is a nonprovisional application claiming benefit of Venezuelan Patent Application No. 2450-01, filed Nov. 22, 2001, the content of which is hereby incorporated in its entirety.
The Faustoval Double Bellows is a recoverable gas lift valve that can be seated in a gas lift pocket mandrel in an oil well. The gas is accumulated into the casing and can pass intermittently to the tubing in order to lift the liquid slug. Due to the fact that this valve contains two bellows, the upper one can control the opening casing pressure and the lower one, the closing casing pressure. This spread of the casing pressure can allow an adequate gas injection volume in order to lift the liquid slug to surface.
When an oil reservoir is almost depleted, it is still possible to obtain commercial production by the intermittent gas lift method, using three different gas lift valves available in the market, which are: a) pressure operated, b) pilot valve, also casing pressure operated, and c) gas lift valve to sensitive liquid pressure. Because all these valves have only one nitrogen charged pressure bellow, they cannot control independently the opening and closing casing pressure. Besides, in most cases, the casing spread is not big enough to deliver the necessary amount of gas to lift the liquid slug to the surface. In this case, the gas lift injection cannot be supplied by a surface choke, and it is necessary to install an intermittent gas lift controller.
British Patent Application No. 8024430, dated Jul. 25, 1980, and entitled xe2x80x9cAdvanced Semiconductor Materials S.V.xe2x80x9d is a device of double bellows to control the gas or liquid rate, according to the position of an external actuator. The function of the double bellows is to balance the internal force in order that the actuator can operate smoothly with little force. This is due because the bellows and the valve seat have the same surface areas. This valve cannot control any pressure, only control the flowing rate, according to the position of the external actuator, but the Faustoval Double Bellows can control independently the upstream, opening and closing pressures.
Soviet Patent Application No. 4473599/93, dated Sep. 15, 1991, is a gas lift valve that opens when the tubing pressure is bigger than the internal bellow pressure. This valve cannot control independently the opening and closing pressure, but the Faustoval Double Bellows is able to do it.
The phase of this process is done by the functionally of the Faustoval which can assure an adequate pressure spread in the casing, which is able to produce the liquid slug to the surface, and can replace the surface gas lift controller. In addition, it reduces the capital cost, simplifies the surface operations and avoids the sudden pressure reduction of the surface gas lift injection line, which can eventually affect the gas injection in other gas lift wells.